The invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions containing modified, for example the grafting of alcohol, aliphatic or aromatic alcohols on colloidal silica particles, and which particles can be selected for toners with rapid admix, excellent flow, and acceptable triboelectrical characteristics. In embodiments, there are provided in accordance with the present invention toner compositions comprised of resin particles, pigment particles, optional charge additives such as quaternary ammonium hydrogen bisulfates, including distearyl methyl hydrogen ammonium bisulfates; distearyl dimethyl ammonium methyl sulfate; alkyl pyridinium halides; metal complexes such as aluminum complexes, reference U.S. Pat. No. 4,845,003, the disclosure of which is totally incorporated herein by reference; TRH, reference U.S. Pat. Nos. 4,758,493 and 4,433,040, the disclosures of which are totally incorporated herein by reference; and, more specifically, 3,5-di-tertiary-butylsalicylic acid, and its salts; BONTRON E-82.TM.; BONTRON E-84 .TM.; BONTRON E-88.TM.; halogenated salicylic acids; LR 120.TM., available from Carlit Inc. of Japan, and the like; and modified silica particles. The silica particles can be modified by a process which comprises the reaction thereof with components that will, for example, reduce and regulate the moisture content thereof enabling the generation of a higher negative toner tribo, especially a higher tribo at 80 percent relative humidity, and a toner with improved relative humidity resistivity as compared to toners wherein untreated colloidal silica, or hydrophobic silicas commercially available are selected. In embodiments, a number of alcohols can be selected for treating and reacting with the silica surface. Examples of alcohol reactants include aliphatic alcohols, wherein aliphatic is preferably alkyl with from 4 to about 30 carbon atoms. Toners with the aforementioned treated surface additives in embodiments of the present invention possess rapid admix of less than about one minute, extended developer life, stable electrical properties, high image print quality with substantially no background deposits, and improved insensitivity to relative humidity of, for example, from 20 to 80 percent RH. Also, the aforementioned toner compositions usually contain pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof, thereby providing for the development and generation of black and/or colored images. The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics as indicated herein, and maintain their triboelectric charging characteristics for an extended number of imaging cycles exceeding, for example, 1,000,000 in a number of embodiments. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including full color processes and trilevel color processes.
In embodiments of the present invention, the grafted alcoholic silicas can be selected as toner charge additives, toner flow aid additives, and the like. When selected as charge additives, a second known charge additive may also be present. The grafted alcoholic silicas of the present invention can be prepared similar to the process as illustrated in a paper by C. C. Ballard et al. entitled Esterification Of The Surface Of Amorphous Silica, Journal of Physical Chemistry, 65, 20 (1961), the disclosure of which is totally incorporated herein by reference. A similar disclosure is presented in U.S. Pat. No. 2,739,074, the disclosure of which is totally incorporated herein by reference. More specifically, the '074 patent discloses inorganic silicate materials having chemically bonded to the silicon atoms on the surface at least 100 OR groups wherein R is a substituted hydrocarbon radical in which the carbon attached to the oxygen is also attached to at least one hydrogen.
There is illustrated in U.S. Pat. No. 2,657,149, the disclosure of which is totally incorporated herein by reference, an estersil, which is organophilic and preferentially wetted by butanol. Other patents of interest relating to silicas that have been treated include U.S. Pat. Nos. 2,739,075; 2,739,076; 2,739,077; 2,739,078; 3,393,155, and 2,757,098, the disclosures of which are totally incorporated herein by reference.
Illustrated in The Chemistry Of Silica, R. K. Iler, John Wiley and Sons, page 464, 1979, is the adsorption of alcohols, such as hexyl alcohol, from carbon tetrachloride on the surface of silicas that were dehydroxylated. In The Handbook Of imaging Materials, edited by Arthur S. Diamond, page 169, 1991, it is indicated that good flow properties are usually desired and often are critical for toners and that materials such as fumed silicas can be added to the surface of a toners to improve flow, and can improve charge stability of the toner and carrier mixture.
Developer compositions with colloidal silica surface components and charge enhancing additives, which impart a positive charge to the toner resin, are known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions. In this patent, there are disclosed quaternary ammonium compounds with four R substituents on the nitrogen atom, which substituents represent an aliphatic hydrocarbon group having 7 or less, and preferably about 3 to about 7 carbon atoms, including straight and branch chain aliphatic hydrocarbon atoms, and wherein X represents an anionic function including, according to this patent, a variety of conventional anionic moieties such as halides, phosphates, acetates, nitrates, benzoates, methylsulfates, perchlorate, tetrafluoroborate, benzene sulfonate, and the like; U.S. Pat. No. 4,221,856 which discloses electrophotographic toners containing resin compatible quaternary ammonium compounds in which at least two R radicals are hydrocarbons having from 8 to about 22 carbon atoms, and each other R is a hydrogen or hydrocarbon radical with from 1 to about 8 carbon atoms, and A is an anion, for example sulfate, sulfonate, nitrate, borate, chlorate, and the halogens, such as iodide, chloride and bromide, reference the Abstract of the Disclosure and column 3; a similar teaching is presented in U.S. Pat. No. 4,312,933; and similar teachings are presented in U.S. Pat. No. 4,291,112 wherein A is an anion including, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica.
Also, there are disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can impart a positive charge to the toner composition and AEROSIL.RTM. surface additives. Further, there are disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles and pigment particles, and as charge enhancing additives alkyl pyridinium compounds and AEROSIL.RTM. surface additives. Additionally, other documents disclosing positively charged toner compositions with charge control additives and AEROSIL.RTM. surface additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,430, and 4,560,635, which illustrates a toner with a distearyl dimethyl ammonium methyl sulfate charge additive. One disadvantage associated with the charge additive of the '635 patent resides in its apparent inherent instability in some instances thus rendering it substantially unsuitable as a bulk toner constituent in imaging processes, as the additive can thermally and chemically degrade, and react with other toner components.
Toner compositions with negative charge enhancing additives and surface additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The '974 patent discloses negatively charged toner compositions comprised of resin particles, pigment particles, and as a charge enhancing additive ortho-halo phenyl carboxylic acids. Similarly, there are disclosed in the '064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing additives. Toners with colloidal silica surface additives are illustrated in U.S. Pat. Nos. 3,590,000 and 3,800,588, the disclosures of which are totally incorporated herein by reference. Also, U.S. Pat. Nos. 5,256,514 and 5,256,575 illustrate negatively charged toners with certain charge additives adsorbed on silica surfaces. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
Illustrated in copending patent application U.S. Ser. No. 234,074 the disclosure of which is totally incorporated herein by reference, and filed currently herewith is a toner composition comprised of resin, pigment charge additive and a flow aid surface additive comprised of silica of a size diameter of from about 5 to about 40 nanometers, and which silica has been treated with a long chain alcohol. With the present invention, the silica is not merely treated or coated with an alcohol it is grafted thereto by a chemical reaction enabling, for example, a higher toner tribo at high relative humidity, for example 80 percent. Further, in U.S. Pat. No. 5,397,667, the disclosure of which is totally incorporated herein by reference, there is illustrated a negatively charged toner composition comprised of resin, pigment, optional negative inducing charge additive and a flow aid surface additive comprised of metallized hydrophobic silica of a size diameter of from about 5 to about 40 nanometers, and which silica contains adsorbed on its surface a hydrocarbon layer originating from a long chain aliphatic alcohol.